Bottom Line:
It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively.Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized.Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy.

ABSTRACTThe role of functional MRI (fMRI) in the presurgical evaluation of patients with intractable epilepsy is being increasingly recognized. Real-time fMRI is an easily performable diagnostic technique in the clinical setting. It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively. Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized. This review article describes the biophysical basis of blood-oxygen-level-dependent (BOLD) fMRI and the methodology adopted, including the design, paradigms, the fMRI setup, and data analysis. Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy. Finally, the special issues involved in fMRI of epilepsy patients and the various challenges of clinical fMRI are detailed.

Figure 0009: This 22-year-old right-handed male was referred for surgical treatment of medically refractory partial seizures that he had been suffering from the age of 3 years. The video-scalp EEG monitoring confirmed that the origin of the seizures was from the left frontal lobe. Axial (A) and sagittal (B) FLAIR images show a thickened cortex, poor grey-white distinction and underlying white matter hyperintensity in the left frontal area suggestive of focal cortical dysplasia. Inline BOLD fMRI, language area mapping using verb generation task coregistered on axial (C), coronal (D), and sagittal (E) 3D-FLASH images, shows strong left lateralization of language. The lesion is adjacent to the Broca's area. The fMRI helped to define Broca's area, which was preserved during a tailored surgical resection with no postoperative expressive speech deficit. Histopathology confirmed cortical dysplasia

Mentions:
We have noted that visual presentation of the language paradigm gives much better and consistent results as compared to auditory presentation. Secondly, in a multilingual country like India, auditory language tasks may have to be modified according to the primary language of the patient. This can be solved to some extent by showing the nouns as pictures in the verb generation task. In our fMRI language studies we perform both the semantic decision task and the verbal fluency task by visual presentation. The former is done using a discrimination task of word pairs - related/unrelated, judging the meaning of sentences, and identifying grammatically accepted language. These tasks are preferably done in the primary language of the patient. The following two cases illustrate the usefulness of fMRI in language lateralization [Figures 9 and 10].

Figure 0009: This 22-year-old right-handed male was referred for surgical treatment of medically refractory partial seizures that he had been suffering from the age of 3 years. The video-scalp EEG monitoring confirmed that the origin of the seizures was from the left frontal lobe. Axial (A) and sagittal (B) FLAIR images show a thickened cortex, poor grey-white distinction and underlying white matter hyperintensity in the left frontal area suggestive of focal cortical dysplasia. Inline BOLD fMRI, language area mapping using verb generation task coregistered on axial (C), coronal (D), and sagittal (E) 3D-FLASH images, shows strong left lateralization of language. The lesion is adjacent to the Broca's area. The fMRI helped to define Broca's area, which was preserved during a tailored surgical resection with no postoperative expressive speech deficit. Histopathology confirmed cortical dysplasia

Mentions:
We have noted that visual presentation of the language paradigm gives much better and consistent results as compared to auditory presentation. Secondly, in a multilingual country like India, auditory language tasks may have to be modified according to the primary language of the patient. This can be solved to some extent by showing the nouns as pictures in the verb generation task. In our fMRI language studies we perform both the semantic decision task and the verbal fluency task by visual presentation. The former is done using a discrimination task of word pairs - related/unrelated, judging the meaning of sentences, and identifying grammatically accepted language. These tasks are preferably done in the primary language of the patient. The following two cases illustrate the usefulness of fMRI in language lateralization [Figures 9 and 10].

Bottom Line:
It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively.Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized.Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy.

ABSTRACTThe role of functional MRI (fMRI) in the presurgical evaluation of patients with intractable epilepsy is being increasingly recognized. Real-time fMRI is an easily performable diagnostic technique in the clinical setting. It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively. Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized. This review article describes the biophysical basis of blood-oxygen-level-dependent (BOLD) fMRI and the methodology adopted, including the design, paradigms, the fMRI setup, and data analysis. Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy. Finally, the special issues involved in fMRI of epilepsy patients and the various challenges of clinical fMRI are detailed.